1. Field of the Invention
The present invention relates to a technique for decorating a casing by bonding a film to the surface of the casing via an adhesive layer. More specifically, the invention relates to a decoration technique for enhancing the decorativeness of the casing by adding a special-effect material to the adhesive layer by which the film having a polarizing characteristic is bonded to the casing.
2. Description of the Related Art
It has been known in recent years to provide a technique for enhancing the decorativeness of electronic equipment, such as a mobile phone, by laminating a decorative film of a polyethylene terephthalate (PET) resin to the surface of the casing of the electronic equipment. The color of the casing of electronic equipment is an important factor from the viewpoint of decorativeness, and it is important that the color be chosen to match user preferences. When laminating such a decorative film to the casing, the desired color hue is rendered by coloring the decorative film or the casing itself.
On the other hand, a technique for coloring the adhesive layer of the decorative film, rather than coloring the decorative film itself, has been proposed (for example, refer to Japanese Unexamined Patent Publication No. 2006-224324). FIG. 8 shows a cross-sectional structure of an automotive film disclosed in that patent publication. A colored adhesive layer 30 is provided between a base film 11 and a decorative PET film 20. A surface coating layer 40 made of a synthetic resin containing a UV-blocking agent and a protective film layer 60 are formed on top of the decorative PET film 20.
The colored adhesive layer 30 is formed by mixing a pigment, dye, coloring agent, or the like into a synthetic resin, such as an urethane resin or an acrylic resin. This color combines with the color of the underlying base film 11 to produce the desired color. Since the colors of the two layers are seen through the decorative PET film 20, a color of greater depth can be rendered.
However, in the prior art, a multilayer film is formed by forming on top of the base film the decorative PET film provided with a decorative effect. When applying this film to electronic equipment or the like, the manufacturing process requires an additional step for attaching the base film to the electronic equipment or the like. This has led to the problem that the number of process steps for decoration increases. Furthermore, in the prior art, the colored adhesive layer is formed by simply mixing a pigment or the like, and it is only possible to obtain the decorative effect produced by the coloring. Since other special effects such as color hue cannot be rendered, there has been a limit to how well the color can be rendered.
Accordingly, it is an object of the present invention to provide a casing having enhanced decorativeness by bonding a film having a polarizing characteristic to the casing via an adhesive layer, and by designing the adhesive layer so as to render various special effects.